Sandbag dikes are commonly erected along river banks and around valuable properties to prevent flooding. In many instances, leakage through the dikes has been so great that it was very difficult or impossible to pump the water out as fast as it leaks through. Moreover, various techniques have been tried to reduce such leakage. However, there is still a need to reduce such leakage in a cost effective, straightforward manner and which can be provided in a short period of time.